The plantar reflex is a nociceptive segmental spinal reflex that serves the purpose of protecting the sole of the foot. The clinical significance lies in the fact that the abnormal response reliably indicates metabolic or structural abnormality in the corticospinal system upstream from the segmental reflex.

1. PLANTAR REFLEX

2. ◦ In normal individual-stimulation of the skin of the plantar
surface of the foot is followed by plantar flexion of the toes
◦ the response is usually fairly rapid, the small toes flex more
than the great toe, and the reaction is more marked when the
stimulus is along the medial plantar surface.

3. THE BABINSKI SIGN
◦ In disease of the corticospinal system, there may be instead
extension (dorsiflexion) of the toes, especially the great toe,
with variable separation or fanning of the lateral four toes: the
Babinski sign or extensor plantar response

5. ◦ Dorsiflexion of great toe and small toes
◦ Fanning of toes
◦ Dorsiflexion of ankle
◦ Flexion of knee joint
◦ Flexion of hip joint
◦ Contraction of tensor fascia lata

6. ◦ Positioning patient – supine , knees extended , heels should rest in the bed
◦ Prerequisites – rule out ankylosis of great toe
◦ Stimulating agent -a blunt point, such as an applicator stick, handle of a reflex
hammer, a broken tongue blade, the thumbnail, or the tip of a key.
◦ Strength of stimulus - should be firm enough to elicit a consistent response, but as
light as will suffice.
◦ If no response is obtained, progressively sharper objects and firmer applications are
necessary

7. ◦ Site of stimulus- Plantar stimulation must be carried out far laterally, in the S1
root/sural nerve sensory distribution
◦ The stimulus should begin near the heel and be carried up the side of the foot at a
deliberate pace, not too quickly, usually stopping at the metatarsophalangeal joints.
◦ The response has usually occurred by the time the stimulus reaches the midportion of
the foot. If the response is difficult to obtain, the stimulus should continue along the
metatarsal pad from the little toe medially but stopping short of the base of the great
toe.
◦ The most common mistakes are insufficiently firm stimulation, placement of the
stimulus too medially, and moving the stimulus too quickly so that the response does
not have time to develop.

8. ◦ Reinforcement of plantar reflex- reinforced by rotating the patient’s head to the opposite side.
◦ Puusepp’s sign is tonic, slow abduction of the little toe on plantar stimulation and may be
present when great toe extension is absent.

9. ◦ The Babinski sign is a part of the primitive flexion reflex. The central nervous system is
organized according to movement patterns, and one of the most basic patterns is avoidance or
withdrawal from a noxious stimulus.
◦ In higher vertebrates, the flexion response includes flexion of the hip and knee, and dorsiflexion
of the ankle and toes, all serving to remove the threatened part from danger
◦ In human infants, the primitive flexion response persists, and an extensor plantar response is
normal in infancy

10. ◦ Maturation of the descending motor systems suppresses the primitive flexion response. This
may be necessary for normal ambulation, or else our legs and feet might be whipping into
flexion unexpectedly, just from stepping on a pebble.
◦ The corticospinal tract is myelinated by about the end of the first year of life, about the time
babies begin to walk.
◦ When there is disease involving the corticospinal tract, the primitive flexion response may
reappear, and the first clinical evidence of this is the Babinski sign.

11. Triple flexion response
◦ With more severe and extensive disease, the entire flexion response emerges, so that
stimulation of the sole causes dorsiflexion not only of the toe, but also the ankle, as well as
flexion of the hip and knee (which for some perplexing reason has four parts)
◦ In addition, there is often contraction of the tensor fascia lata causing slight internal rotation at
the hip and more rarely abduction of the hip (Brissaud’s reflex)
◦ These movements are all part of a spinal defense reflex mechanism, also known as the reflex of
spinal automatism (Marie), the pathologic shortening reflex, reflex flexor synergy, the withdrawal
reflex, mass flexion reflex, and the réflexe or phénomène des raccourcisseurs.
◦ The response may be bilateral and is then called the crossed flexor reflex.

14. Problems in Interpreting the Plantar Response
◦ The most common problem is distinguishing an upgoing toe from voluntary withdrawal,
especially when the plantar surface of the foot is unusually sensitive
◦ If the patient is ticklish, it may help to simply hold the ankle firmly. Some believe withdrawal is
less if the patient performs the plantar stimulation himself (an auto-Babinski)
◦ Some patients have no elicitable plantar response, in which case the plantars are said to be
mute or silent.

15. ◦ Toe extension may occasionally fail to occur because of disruption of the lower motor neuron
innervation to the EHL
(e.g., radiculopathy, peroneal nerve palsy, peripheral neuropathy, amyotrophic lateral sclerosis
[ALS]),
in which case the toe is paralyzed for voluntary contraction as well.
◦ Frontal lobe lesions may cause a hyperactive plantar grasp reflex , driving the toes downward.

16. ◦ With extensive disease involving both the basal ganglia and the corticospinal tract, there may
be no extensor response.
◦ Intact extrapyramidal pathways are essential to its production.
◦ The extensor plantar response does not occur in lesions of the basal ganglia alone; its
presence in some extrapyramidal disorders, such as Parkinson’s disease,suggests associated
corticospinal tract involvement.
◦ Paralysis of the toe flexors may cause a false-positive extensor plantar response.

17. ◦ An extensor plantar response does not always signify structural disease
◦ it may occur as a transient manifestation of physiologic dysfunction of the corticospinal
pathways.
◦ A Babinski sign may sometimes be found in
◦ deep anesthesia and narcosis, in drug and alcohol intoxication, in metabolic coma such as
hypoglycemia, in deep sleep, postictally.
◦ During Cheyne-Stokes respirations, an upgoing toe may appear during the apneic phase
anddisappear during the phase of active respiration.

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